<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<button id="btn01" onclick="toClick()">click me</button>
		<script>
			function toClick() { //被覆盖
				console.log('first');
			}

			function toClick() {
				console.log('second');
			}
		</script>
	</body>
</html>
